Laboratory of Movement Analysis and Measurements, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Gait Posture. 2013 Feb;37(2):229-34. doi: 10.1016/j.gaitpost.2012.07.012. Epub 2012 Aug 9.
Time periods composing stance phase of gait can be clinically meaningful parameters to reveal differences between normal and pathological gait. This study aimed, first, to describe a novel method for detecting stance and inner-stance temporal events based on foot-worn inertial sensors; second, to extract and validate relevant metrics from those events; and third, to investigate their suitability as clinical outcome for gait evaluations. 42 subjects including healthy subjects and patients before and after surgical treatments for ankle osteoarthritis performed 50-m walking trials while wearing foot-worn inertial sensors and pressure insoles as a reference system. Several hypotheses were evaluated to detect heel-strike, toe-strike, heel-off, and toe-off based on kinematic features. Detected events were compared with the reference system on 3193 gait cycles and showed good accuracy and precision. Absolute and relative stance periods, namely loading response, foot-flat, and push-off were then estimated, validated, and compared statistically between populations. Besides significant differences observed in stance duration, the analysis revealed differing tendencies with notably a shorter foot-flat in healthy subjects. The result indicated which features in inertial sensors' signals should be preferred for detecting precisely and accurately temporal events against a reference standard. The system is suitable for clinical evaluations and provides temporal analysis of gait beyond the common swing/stance decomposition, through a quantitative estimation of inner-stance phases such as foot-flat.
步态支撑相的时间段可以作为有临床意义的参数，揭示正常和病理步态之间的差异。本研究首先旨在描述一种基于足部穿戴惯性传感器检测支撑相和内支撑相时间事件的新方法；其次，从这些事件中提取和验证相关指标；最后，研究它们作为步态评估的临床结果的适用性。42 名受试者，包括健康受试者和踝关节炎手术前后的患者，在穿着足部穿戴惯性传感器和压力鞋垫的情况下进行了 50 米行走试验，作为参考系统。基于运动学特征，提出了几个假设来检测足跟触地、足趾触地、足跟离地和足趾离地。在 3193 个步态周期中，将检测到的事件与参考系统进行了比较，结果显示具有良好的准确性和精密度。然后，对绝对和相对支撑期，即负荷反应、足平底和蹬离期进行了估计、验证和统计学比较。除了支撑期持续时间的显著差异外，分析还显示了不同的趋势，即健康受试者的足平底明显较短。结果表明，相对于参考标准，惯性传感器信号中的哪些特征应该优先用于精确和准确地检测时间事件。该系统适用于临床评估，并通过对内支撑相（如足平底）的定量估计，提供超越常见摆动/支撑分解的步态时间分析。
